1. Field
This invention relates to cannulas of the type used to perform minimally invasive surgery and, more particularly, to cannulas that allow a minimally invasive surgical instrument to be serviced without being removed from the cannula.
2. Background
Minimally invasive surgery (MIS) (e.g., endoscopy, laparoscopy, thoracoscopy, cystoscopy, and the like) allows a patient to be operated upon through small incisions by using a camera and elongated surgical instruments introduced to an internal surgical site. The surgical site often comprises a body cavity, such as the patient's abdomen. The body cavity may optionally be distended using a clear fluid such as an insufflation gas. In traditional minimally invasive surgery, the surgeon manipulates the tissues by using hand-actuated end effectors of the elongated surgical instruments while viewing the surgical site on a video monitor.
One or more cannulas may be passed through small (generally 1 inch or less) incisions or a natural body orifice to provide entry ports for the minimally invasive (e.g., endoscopic, laparoscopic, and the like) surgical instruments, including a camera instrument (e.g., endoscope, laparoscope, and the like). A surgeon is able to perform surgery by manipulating the surgical instruments externally to the surgical site under the view provided by the camera instrument.
Manipulating minimally invasive surgical instruments may be more difficult than using conventional surgical instruments in open surgery because of the need to manipulate the instruments by means of the elongate shafts, which are constrained in their movement by the need to avoid translation of the instrument where it enters the patient. Robotic surgery allows minimally invasive surgical instruments to be manipulated by servo controllers that the surgeon controls from a remote console. The use of servo controllers and robotic surgery allows more precise and intuitive control of the surgical instruments and simplifies for the surgeon the considerations of the motion constraints on the surgical instruments.
It is typical to provide several cannulas for a minimally invasive surgical procedure. Generally each cannula will provide access to the surgical site for a single surgical or camera instrument. For example, four cannulas may be provided with one cannula being used to introduce a camera instrument and the remaining three cannulas being used to introduce surgical instruments. While the small incisions necessary for placing a cannula are less traumatic than the incision necessary for open surgery, each incision still represents a trauma to the patient.
In an effort to reduce the trauma of minimally invasive surgery even further, techniques are being developed to allow minimally invasive surgery using only a single cannula. This may be accomplished by using a somewhat larger cannula that can accommodate all of the instruments required for the surgery. Minimally invasive surgery performed through a single cannula may be referred to as single port access (SPA) surgery. The single cannula may be introduced through a body orifice and be referred to as Natural Orifice Transdermal Endoscopic Surgery (NOTES). Single port surgery may also be referred to as bellybutton surgery when the navel (umbilicus) is used as the location for the single cannula.
Minimally invasive single port surgery may in some instances be more difficult and time-consuming than minimally invasive surgery using multiple entry ports. One aspect that may increase the time required when using a single cannula for all instruments is the difficulty of inserting a surgical instrument into the cannula because of the lack of space around the cannula where multiple instruments are located. During the course of a surgical procedure, it may be necessary to remove and reinsert a surgical instrument multiple times in order to service the instrument in various ways. For example, it may be necessary to remove and reinsert an instrument to remove an object, such as a sponge or specimen, from the surgical site. As another example, it may be necessary to remove and reinsert an instrument to supply a clamp or a suture to the surgical site. As yet another example, it may be necessary to remove and reinsert an instrument to clean the instrument, such as cleaning the lens or illumination port on a camera instrument. Removing and re-inserting surgical instruments may consume a substantial amount of time and disrupt the progress and workflow of the surgical procedure. The time and disruption created by removing and re-inserting surgical instruments may be greater when the instruments are controlled by robotic actuators because the actuators further crowd the space around the cannula.
In view of the above, it would be desirable to provide an improved apparatus and method for carrying out minimally invasive surgical procedures that reduces the need for removing and reinserting surgical instruments and/or camera instruments into the cannula.